Development of a micromechanical finite element model from computed tomography images for shear modulus simulation of asphalt mixtures

The main objective of this study was to develop 2D and 3D micromechanical finite element (FE) models to predict the shear modulus of two asphalt mixture types, PG 64-28 PM (dense-graded polymer modified mixture) and RHMA-G (gap-graded rubberized mixture). The internal microstructure of the asphalt mixtures were determined by X-ray computed tomography (CT) imaging. X-ray CT images were processed to create 2D and 3D meshed asphalt mixture FE model structures. Meshed model structures were exported to the FE modeling software ABAQUS. Elastic and viscoelastic assumptions were used for modeling aggregate and mastic subdomains, respectively. Shear modulus predictions for 2D and 3D models were compared to the measured values to determine the effectiveness of each model type for the simulation of the shear frequency sweep at constant height (FSCH) test. It was concluded that the 3D micromechanical FE model is capable of predicting shear modulus at relatively high test temperatures with high accuracy across a range of loading frequencies. On the other hand, 2D numerical models always under predicted the shear modulus values at all simulation temperatures and loading frequencies because the reduced microstructure for the 2D models decreased the accuracy of numerical predictions. It is expected that developed 3D models will serve as a valuable tool to understand certain problems in the current design methods of asphalt concrete pavements.